The US Transportation Security Administration (TSA) has confirmed that it was cancelling a contract for X-ray body scanners manufactured by the Rapiscan company because the firm was not able to meet a deadline set by the US Congress to provide less invasive Automated Target Recognition (ATR) software.

The American Civil Liberties Union advises travellers on its website that TSA agents "will see an image of your body that could include a revealing look at your entire body, including breasts, genitals, buttocks and external medical devices".

"By June 2013, travellers will only see machines which have ATR that allow for faster throughput," the TSA said in a statement.

"This means faster lanes for the traveller and enhanced security," it added.

The revealing body scanners were first tested in 2007, prompting public outcry and quickly becoming the butt of late-night talk show jokes.

The Electronic Privacy Information Center (EPIC) argued in a letter to US Homeland Security Secretary Janet Napolitano that "there are less intrusive and less costly techniques available to address the risk of concealed explosives on aircrafts".

Nationwide, there are 174 scanners that project the images of "nude" passengers to TSA workers located in a separate room. Those units will be replaced by the end of May, according to the TSA.

"It's not about passenger complaints. It's about requiring Rapiscan to deploy non-imaging software by the deadline, and we've determined they can't do that," a TSA spokesperson said.